alternator/water pump drive belt

wato · Postby **wato** » Sun Dec 16, 2018 3:26 pm

Hello!
I have a 1999 mx5 and decided to replace both drive belts. I bought Gates belts 3pk895 for the alt/water pump and gates 4pk950 for the a/c and power steering. Both belts were the recommended part numbers on the gates australia web site, and the place i bought them from said so as well. However, the belt for the alternator and water pump appears to be a couple of mm not wide enough compared to the belt on the car. I checked it with a 2000 mx5 and the new belt is not the same width compared to that either. So the 1999 and 2000 mx5's belts are the same width and sit snugly on the alternator but the new belt is 2mm or so short. What do people on this forum use? If i used the gates would be asking for problems? Thanks all!

bruce · Postby **bruce** » Sun Dec 16, 2018 3:50 pm

Is it not LONG enough or is the WIDTH of the belt difft (fewer ribs)?
I'd suspect the old belt has stretched with age. Thus new one should fit as you can adjust the placement of the alternator to accomondate the slightly SHORTER belt.

RS2000 · Postby **RS2000** » Sun Dec 16, 2018 6:56 pm

wato, the 3pk0895 has 3 ribs & is 895mm long(circumference). My 99 NB has a 4pk0890, which is a 4 rib belt.
I'd guess 3 ribs will work, but may wear out quicker if more tension is required to drive.

93_Clubman · Postby **93_Clubman** » Sun Dec 16, 2018 7:10 pm

IRCC, all NA & NB belts are 4pk, ie 4 ribs not 3pk, ie 3 ribs, so website typo.

manga_blue · Postby **manga_blue** » Mon Dec 17, 2018 6:24 am

As clubman says, MX5 engines use 4 ribbed belts. I just put a pair of Gates belts on my NA8: 4PK940 and 4PK885

wato · Postby **wato** » Mon Dec 17, 2018 7:53 am

As i stated, the belt appears to be about 2mm not wide enough. Ill give gates a ring and let them know. The belt isn't even ribbed. thanks for all the replies

manga_blue · Postby **manga_blue** » Mon Dec 17, 2018 8:59 am

A rib is a sort of micro-groove on the pulley side of the belt. A 3PK will have 3 of them, A 4PK will have 4 and the 4 rib belt will be 2 or 3 mm wider than a 3.

In the numbering system for belts the first number is the number of ribs e.g. 3 or 4 and the second is the length in mm. So 4PK950 is 4 ribs and 950mm long.

wato · Postby **wato** » Mon Dec 17, 2018 11:16 am

trying a find the correct belts is proving challenging. I went to sparesbox.com.au and put in a search for the belts, a window comes up and says so and so is the correct belt with fitment guaranteed, when i click to view the details it tells me it won't fit! And im getting the same problems at another site and on ebay. Soooo can anyone give me the correct part numbers for both drive belts for a 1999 nb mazda mx5 with power steering and air con? Before it does my head in lol lol. many thanks

hks_kansei · Postby **hks_kansei** » Mon Dec 17, 2018 11:46 am

I just went to Bursons or Repco, cant remember which, and asked for belts for an NB etc.

They just grabbed them and handed them over, no issues.

Only issue I had was that I forgot to specify that I had AC on my car, so the original belt was too short. But they swapped it no issue.

RS2000 · Postby **RS2000** » Mon Dec 17, 2018 3:28 pm

Definitely 4PK0885 for the alternator on mine. I'd say 4PK0880 or 0890 would also do, as 5mm different in length will mean the alternator only moves by a couple of mm. My p/s & a/c are long gone.
If you still have the old belt, it should have the number on the outside, but if not readable, measure the length or take the belt to any repco/bursons etc.

manga_blue · Postby **manga_blue** » Mon Dec 17, 2018 3:34 pm

All I did was read the numbers off the old belts and ordered them from sparesbox on ebay without worrying what sort of car they were meant to fit. That's how I got 4PK940 and 4PK885. My order with them said they were actually for some sort of Kia van, but only the sizes and rib numbers mattered to me.

The belt setup on mine is the same as yours: BP engine with PS and A/C. You could order the same as me but you'll find they're a tight fit to get on. Otherwise you could give yourself a slightly easier time and go with the sizes you originally had, except with the right number of ribs, i.e. 4PK950 and 4PK895.

wato · Postby **wato** » Mon Dec 17, 2018 3:54 pm

well i must have stopped the engine at the right time because i can see the part numbers on the belt now. the alt/wp number is 4pk885 and the a/c and p/s belt is 4pk925, both are dayco belts. Pity i didn't see that before! Anyway thanks for everyones help!

manga_blue · Postby **manga_blue** » Mon Dec 17, 2018 9:53 pm

If you‘ve already got a 4PK950 then I would try that first. It may well fit. A 4PK925 may be a very tight fit and a big struggle to get on. BTW Gates and Dayco belts are both good brands and will be adequate for the job. I would take them over whatever Mazda sell any day.